The present invention relates to a heat exchanger which is suitably used as an evaporator of a car air conditioner, which is a refrigeration cycle to be mounted on an automobile, for example.
In this specification and appended claims, the downstream side (a direction represented by arrow X in the drawings) of an air flow through air-passing clearances between adjacent heat exchange tubes will be referred to as the “front,” and the opposite side as the “rear.” Further, the upper, lower, left-hand, and right-hand sides of FIG. 2 will be referred to as “upper,” “lower,” “left,” and “right,” respectively.
The present applicant has proposed a heat exchanger which is used as an evaporator and which satisfies the requirements for reduction in size and weight and higher performance (refer to Japanese Patent Application Laid-Open (kokai) No. 2009-97776). The heat exchanger includes a heat exchange core section including a plurality of heat exchange tubes disposed such that their longitudinal direction coincides with the vertical direction, and header tanks disposed on the upper and lower sides of the heat exchange core section such that their longitudinal direction coincides with the direction of the row (arrangement direction) of the heat exchange tubes. Each header tank is composed of a tank main body which is open at opposite ends thereof, and end members which are brazed to the opposite ends of the tank main body so as to close the openings at the opposite ends. The tank main body of each header tank is composed of a first member which forms a portion of the tank main body on the side toward the heat exchange core section and to which the heat exchange tubes are connected, a second member which forms the remaining portion of the tank main body, and a third member which is disposed between the first member and the second member and is brazed to these members and which has a partition portion for vertically dividing the interior of the header tank into two spaces. The first member and the second member have, at each of front and rear side edges thereof, vertical wall portions which partially overlap each other as viewed from the front side and which are provided such that each vertical wall portion of the second member is located on the inner side of the corresponding vertical wall portion of the first member with a gap formed therebetween. The third member has, at each of the front and rear side edges thereof, a vertical wall portion which is disposed in the gap between the corresponding vertical wall portions of the first and second members and is brazed to the vertical wall portions, and a horizontal wall portion which is provided at the distal end of the vertical portion and projects outward in the front-rear direction and to which the distal end of the corresponding vertical wall portion of the first member is brazed. Each of the end members of each header tank has engagement claws which project toward the longitudinal center of the header tank and which are brazed to the tank main body in a state in which the engagement claws are engaged with the tank main body.
In the heat exchanger disclosed in the above-mentioned publication, each header tank has two header sections which are juxtaposed in the air flow direction and whose longitudinal direction coincides with the longitudinal direction of the header tank. A heat exchange tube group composed of a plurality of heat exchange tubes disposed at intervals in the longitudinal direction of the header tank is provided between each of the header sections of the upper header tank and a corresponding one of the header sections of the lower header tank. Upper end portions of the heat exchange tubes of the heat exchange tube groups are connected to the corresponding header sections of the upper header tank, and lower end portions of the heat exchange tubes of the heat exchange tube groups are connected to the corresponding header sections of the lower header tank. Each header section is formed by brazing caps to opposite ends of a tubular body which is open at the opposite ends, to thereby close the openings at the opposite ends of the tubular body. A refrigerant inlet is provided in one of the caps of the leeward header section of the upper header tank, and a refrigerant outlet is provided in the cap of the windward header section of the upper header tank, the cap being located at the end where the refrigerant inlet is provided.
The heat exchanger disclosed in the above-mentioned publication is manufactured by brazing all the components together in a furnace in a state in which all the components are assembled and provisionally fixed by an appropriate jig.
However, the heat exchanger disclosed in the above-mentioned publication has a possibility that, when the provisionally fixed assembly of all the components is placed in the brazing furnace during the manufacture of the heat exchanger, the end members may come off the combination of the first to third members which constitute the tank main body of the header tank.
In order to solve such a problem, the present applicant has proposed an improved heat exchanger (refer to Japanese Patent Application Laid-Open (kokai) No. 2011-64379). In the improved heat exchanger, the first member of the tank main body of each header tank has, at each of the longitudinal opposite ends of each vertical wall portion, a protrusion which extends straight from the vertical wall portion toward the side opposite the heat exchange tubes. The engagement claws of each end member of the header tank has first and second portions. The first portion extends, along the edge of the protrusion opposite the heat exchange tubes and beyond the protrusion, toward the longitudinal center of the tank main body. The second portion projects from the distal end of the first portion toward the heat exchange tubes, and comes into engagement with the edge of the protrusion of the first member located on the side toward the longitudinal center of the header tank. According to the heat exchanger disclosed in the second publication, it is possible to prevent the end members from coming off the tank main body to the outer side with respect to the longitudinal direction thereof when the provisionally fixed assembly of all the components is placed in the brazing furnace during the manufacture of the heat exchanger.
However, the heat exchanger disclosed in the second publication has a possibility that, when the provisionally fixed assembly of all the components is placed in the brazing furnace during the manufacture of the heat exchanger, the first to third members which constitute the tank main body of the header tank positionally shift because of an insufficient force for restraining the combination of the first to third members from the front and rear sides.